If done right, recomputation can be very efficient when failures do occur while bearing no cost during failure-free periods. Thus, the need for data replication can be greatly reduced. We present RCMP (name derived from the word recomputation) a system that performs efficient job recomputations in the context of the popular MapReduceparadigm.While extendingthe MapReducemodel with support for efficient job recomputations is important and practically relevant given its popularity, we believe that our work on the importance and challenges of job recomputation transcends the MapReduce paradigm.